This triangle map was inspired by a UK election map in the Financial Times created by Billy Ehrenberg. This map below shows voting results in Wisconsin by county comparing 2012 to 2016 and where Clinton lost compared to Obama. If you are interested in a how-to post let me know in the comments below. Data source: Wikipedia.

The gauge chart is an oft-maligned chart type. It has a poor data-to-ink ratio and it's difficult to interpret accurately. But I think it has some merit. Firstly, it is a very familiar chart type that most people can interpret it consistently. After all, it has been used on car dashboards since the Model-T.Gauges also have value when on a mobile dashboard displaying a single metric. The gauge uses more vertical real estate and it still difficult to interpret accurately. But I have found it is less confusing than a bullet chart in this instance. Bullet charts are hard to read because the origin point is confusing without multiple reference bars to compare. Furthermore, bullet charts are generally more confusing than gauges because they are new to most people. But, most people have seen a gauge and can consistently interpret the bands and reference points. Also a bullet charts require more horizontal real estate which is more valuable on a mobile device than a desktop since the aspect ratios are flipped.Here is a side-by-side comparison of both chart types in a mobile dashboard in Tableau. See my review of the strengths and weaknesses below. Please let me know your thoughts below.